Datasheet

AD7321 Data Sheet
Rev. B | Page 26 of 36
SEQUENCER OPERATION
The AD7321 can be configured to convert a sequence of
consecutive channels (see Figure 44). This sequence begins by
converting on Channel 0 and ends with a final channel as selected
by Bit ADD0 in the control register. In this configuration, there is
no need for a write to the sequence register. To operate the AD7321
in this mode, set Seq1 to 1 and Seq2 to 0, and then select the final
channel in the sequence by programming Bit ADD0 in the control
register.
Once the control register is configured to operate the AD7321
in this mode, the DIN line is held low, or the write bit is set to 0.
To return to traditional multichannel operation, a write to the
control register to set Seq1 to 0 and Seq2 to 0 is necessary.
When Seq1 and Seq2 are both set to 0, or when both are set to 1,
the AD7321 is configured to operate in traditional multichannel
mode, where a write to Channel Address Bit ADD0 in the control
register selects the next channel for conversion.
DIN: WRITE TO RANGE REGISTER TO SELECT THE RANGE
FOR THE ANALOG INPUT CHANNELS.
DOUT: CONVERSION RESULT FROM CHANNEL 0, ±10V
RANGE, SINGLE-ENDED MODE.
CS
DIN: WRITE BIT = 0 OR DIN LINE HELD LOW TO CONTINUE
THROUGH SEQUENCE OF CONSECUTIVE CHANNELS.
DOUT: CONVERSION RESULT FROM CHANNEL1, RANGE AS
SELECTED IN RANGE REGISTER.
CS
DIN: WRITE BIT = 0 OR DIN LINE HELD LOW TO CONTINUE
TO CONVERT THROUGH THE SEQUENCE OF
CONSECUTIVE CHANNELS.
DOUT: CONVERSION RESULT FROM CHANNEL 0, RANGE AS
SELECTED IN RANGE REGISTER.
CS
DIN: WRITE TO CONTROL REGISTER TO SELECT THE FINAL
CHANNEL IN THE CONSECUTIVE SEQUENCE, SET Seq1 = 1
AND Seq2 = 0. SELECT OUTPUT CODING FOR SEQUENCE.
DOUT: CONVERSION RESULT FROM CHANNEL 0,
RANGE SELECTED IN RANGE REGISTER 1,
SINGLE-ENDED MODE.
CS
POWER ON.
DIN TIED LOW/WRITE BIT = 0.
CONTINUOUSLY CONVERT
ON CONSECUTIVE SEQUENCE
OF CHANNELS.
DIN: WRITE TO CONTROL
REGISTER TO STOP THE
SEQUENCE, Seq1 = 0, Seq2 = 0.
DOUT: CONVERSION RESULT
FROM CHANNEL IN SEQUENCE.
CS
STOPPING
A SEQUENCE.
05399-032
Figure 44. Flowchart for Consecutive Sequence of Channels